The major goal is to identify schistosome proteins important in immunity and development through the use of recombinant DNA technology. To accomplish this goal we will take advantage of the fact that in concomitant or attenuated parasite immunity, there are species of antibody molecules that recognize determinants on the surface of the schistosomule that mediate a schistosomicidal response. These antibodies provide appropriate reagents for isolating relevant antigens, when used in conjunction with recombinant DNA technology. By isolating the DNA encoding an important antigen, we can sequence the gene and deduce the amino acid sequence of the antigen, produce reasonable quantities of the antigen in bacteria for vaccine testing, create a synthetic recombinant vaccinia virus encoding the antigen, or create a modified antigen that may function even better than the native one in producing immunity. In addition, the availability of purified protein antigens will allow us to develop monospecific sera which, together with the DNA encoding the antigens will be useful in exploring the control and expression of these proteins during development. By assessing the efficacy of identified antigens in protection experiments we will be able to identify those that are relevant. Once relevant antigens are identified, we will assess recombinant vaccinia virus as a mode of antigen presentation.